1. Field of the Invention
The present invention relates to the servicing of elevated cables or installations, such as high voltage power lines and, more particularly, pertains to a new basket structure suited for supporting workmen during servicing operations.
2. Description of the Prior Art
Over the years, various helicopter portable basket structures have been developed for servicing elevated cables or installations, such as high voltage power transmission lines. For instance, U.S. Pat. No. 4,478,312 issued on Oct. 23, 1984 to Kurtgis, U.S. Pat. No. 4,422,528 issued on Dec. 27, 1983 to Patterson and Canadian Patent laid-open application No. 2,055,639 filed on Nov. 15, 1991 in the names of De Forges de Parny et al. all disclose a basket structure suspended on rope slings from a helicopter by means of an appropriate lifting harness system. Such arrangements, wherein the basket structure is supported underneath the helicopter, suffer from several disadvantages. For instance, in the case of a malfunctioning of the helicopter implying an emergency landing, the basket structure has to be dropped to permit landing of the helicopter. Furthermore, when the basket structure is disposed at the end of downwardly depending slings as mentioned hereinbefore, the helicopter pilot is not in a position to accurately assess the position of the basket structure, thereby rendering the installation thereof on elevated cables quite arduous and time consuming.
Accordingly, attempts have been made to overcome the above mentioned drawbacks. For example, U.S. Pat. No. 5,328,133 issued on Jul. 12, 1994 to Charest et al. discloses a basket structure which is removably mounted at one end of a support arm extending laterally outwardly of a helicopter.
Although the system described in the above mentioned patent constitutes an improvement over previously known helicopter basket carrying systems, it has been found that there is a need for a new basket structure adapted to be carried in a compact manner by a helicopter in order to provide additional clearance to the rotor blades of the helicopter, while still providing the required clearance above ground level during take-off and landing operations.